Panasonic is preparing to unveil a slimmed-down version of its 20-hour methanol fuel-cell battery.

The company said that the latest prototype will feature the same capacity as its predecessor in a casing roughly half the size of the previous prototype first displayed at the 2006 CES conference in Las Vegas.

The new prototype is being demonstrated in both a 270cc casing designed for notebook use and a larger 360cc system which can be used to provide external power for other devices. Both models offer some 20 hours of power at a 10W output level.

The prototypes are set to be unveiled later this week at an event in Japan. The company has reportedly set 2012 as the target release date for the first of its methanol battery systems.

Methanol cell batteries have been under development for several years as a possible replacement for lithium-ion units. Direct methanol fuel cell systems are said to be cheaper and less volatile than hydrogen fuel cells.